Facilitator control as automatic behavior: A verbal behavior analysis

Several studies of facilitated communication have demonstrated that the facilitators were controlling and directing the typing, although they appeared to be unaware of doing so. Such results shift the focus of analysis to the facilitator's behavior and raise questions regarding the controlling variables for that behavior. This paper analyzes facilitator behavior as an instance of automatic verbal behavior, from the perspective of Skinner's (1957) book Verbal Behavior. Verbal behavior is automatic when the speaker or writer is not stimulated by the behavior at the time of emission, the behavior is not edited, the products of behavior differ from what the person would produce normally, and the behavior is attributed to an outside source. All of these characteristics appear to be present in facilitator behavior. Other variables seem to account for the thematic content of the typed messages. These variables also are discussed.

The relationship between stimulus equivalence and verbal behavior

Despite the apparent similarity between stimulus equivalence and verbal behavior, these phenomena have been described in different terms. With different terminologies for each phenomenon, the precise nature of their relationship is difficult to determine. To explore this relationship, this paper first defines stimulus equivalence using a synthesis of the mathematical definition of the equivalence relation and Sidman and Tailby's (1982) definition. Selected examples of stimulus equivalence are then described as verbal behavior using Skinner's (1957) terminology. The paper then cites instances of verbal behavior that cannot be described as stimulus equivalence and considers whether there are instances of stimulus equivalence that cannot be described as verbal behavior.

Variable-interval schedule performance in open and closed economies

In two experiments, pigeons obtained food according to variable-interval schedules. In the first experiment, equivalent variable-interval schedules with average interreinforcer intervals ranging between 10 and 80 s in different conditions were studied in both open and closed economies. Response rates increased as reinforcement frequency decreased in the closed economy. By contrast, in the open economy response rates decreased for 1 bird and were variable for the other as reinforcement frequency decreased. The second experiment showed that the differences in the functions between responding and reinforcement frequency in the two types of economies were not due to changes in deprivation level. These results suggest that open and closed economies yield different behavioral effects. This conclusion is supported further by a reconsideration of previous findings that appear counter to the conclusion.

Determination of lesion volume by MRI and stereology in a macaque model of tuberculosis

Sensitive and reproducible methods are needed to measure the impact on the host following experimental challenge with Mycobacterium tuberculosis, in order to determine the degree of protection conferred by new vaccines. Here we compare how well different clinical and post-mortem measures of disease burden predict the response by the host to increasing doses of M. tuberculosis in rhesus and cynomolgus macaques. The total lung and lesion volume was quantified from magnetic resonance imaging (MRI) digital stacks obtained from lungs of M. tuberculosis infected animals that were formalin fixed and scanned ex-vivo. The total lung lesion volume relative to the fixed whole lung volume was superior at indicating disease burden when compared to thoracic radiography, pathology scores, changes in body weight and temperature, as well as erythrocyte haemoglobin concentrations and sedimentation rate. The total lesion volume accurately reflected differences in challenge doses of M. tuberculosis that ranged from 30 to 500 CFU delivered by aerosol. The determination of total lesion volume from MR images demonstrated a species-dependent difference between rhesus and cynomolgus macaques in susceptibility to M. tuberculosis infection. MR stereology provides an accurate, quantifiable and relatively simple assessment, which can be easily standardized between laboratories and should form an essential component of the clinical assessment of disease progression, or vaccine efficacy.

Comparative pathology of infection by novel diarrhoea viruses

Examination of diarrhoeic faeces in the electron microscope often reveals viruses that are presumed to be enteropathogenic. Lesions caused by novel rotaviruses were similar to those of group A rotaviruses, but enterocyte syncytia were seen which are probably pathognomonic for novel rotaviruses. In adenovirus infection in piglets, mature enterocytes were infected and destroyed; intranuclear inclusion bodies were seen in infected enterocytes. Calici-like viruses infected mature enterocytes in calves and the lesions were similar to those described in humans infected with calici-like viruses; in both host species it was impossible to demonstrate virus particles in enterocytes examined in the electron microscope. The Breda virus infected villi and crypts in the lower small intestine and the surface and crypts in the large intestine; it was the only enteropathogenic virus to show this distribution of infection and lesions. Astrovirus infection in lambs was comparable to a mild rotavirus infection, but in calves the epithelium of the dome villi of Peyer's patches was infected. Parvovirus in cats and dogs infected and destroyed small intestinal crypt cells, causing dilated crypts and stunted villi; intranuclear inclusion bodies were prominent.

An assay to compare the infectivity of Mycobacterium tuberculosis isolates based on aerosol infection of guinea pigs and assessment of bacteriology

The aim of this study was to establish an assay to compare Mycobacterium tuberculosis strains, and cells grown under different growth conditions, in terms of their ability to cause a lung infection and disseminate to the spleen. M. tuberculosis strains H37Rv, Erdman, South Indian (TMC120, SI) and H37Rv cells grown aerobically or under low oxygen/iron limitation in a chemostat were assayed for infectivity. Groups of 8 animals were challenged with 3 different doses of each strain. Lung and spleen bacteriology was assessed at 16 days post-infection for all strains. Bacteriology and lung pathology at day 56 was studied for H37Rv, Erdman and SI. Strains H37Rv and Erdman had a statistically significantly higher pathogenic potential than SI and this was confirmed by analysis of lung pathology performed at 8 weeks post-infection, although the Erdman strain caused more extensive caseation without calcification and little encapsulation. The model could discriminate between cells grown under different growth conditions; low-oxygen/iron-limited cells had a significantly higher infectivity than those grown aerobically. This study presents a quick and reliable method for comparing with statistical confidence, the pathogenic potential of M. tuberculosis strains and the impact of in vitro growth conditions on the infectivity of M. tuberculosis in vivo.

Evaluation of vaccines in the EU TB Vaccine Cluster using a guinea pig aerosol infection model of tuberculosis

The TB Vaccine Cluster project funded by the EU Fifth Framework programme aims to provide novel vaccines against tuberculosis that are suitable for evaluation in humans. This paper describes the studies of the protective efficacy of vaccines in a guinea pig aerosol-infection model of primary tuberculosis. The objective was to conduct comparative evaluations of vaccines that had previously demonstrated efficacy in other animal models. Groups of 6 guinea pigs were immunized with vaccines provided by the relevant EU Vaccine Cluster partners. Survival over 17 or 26 weeks was used as the principal measure of vaccine efficacy following aerosol challenge with H37Rv. Counts of mycobacteria in lungs and spleens, and histopathological changes in the lungs, were also used to provide evidence of protection. A total of 24 vaccines were evaluated in 4 experiments each of a different design. A heterologous prime-boost strategy of DNA and MVA, each expressing Ag85A and a fusion protein of ESAT-6 and Ag85B in adjuvant, protected the guinea pigs to the same extent as BCG. Genetically modified BCG vaccines and boosted BCG strategies also protected guinea pigs to the same extent as BCG but not statistically significantly better. A relatively high aerosol-challenge dose and evaluation over a protracted time post-challenge allowed superior protection over BCG to be demonstrated by BCG boosted with MVA and fowl pox vectors expressing Ag85A.

Proteolytic inactivation of the bovine spongiform encephalopathy agent

Thermostable proteases have been investigated for their ability to provide a novel biological solution to decontamination of prion agents responsible for transmissible spongiform encephalopathies (TSEs). Proteases were identified that digested total mouse brain homogenate (MBH) protein from uninfected mice. These proteases were then evaluated for digestion of BSE (301V) infectious MBH over a range of pH and temperatures, screened for loss of anti-prion antibody 6H4 immunoreactivity and protease-treated infectious MBH assessed in mouse bioassay using VM mice. Despite a number of proteases eliminating all 6H4-immunoreactive material, only the subtilisin-enzyme Properase showed a significant extension in incubation period in mouse bioassays following a 30-min incubation at 60 degrees C and pH 12. These results demonstrate the potential of the method to provide a practical solution to the problems of TSE contamination of surgical instruments and highlight the inadequacy of using Western blot for assessment of decontamination/inactivation of TSE agents.

Experimental aerogenic Burkholderia mallei (glanders) infection in the BALB/c mouse

The object of this study was to develop and characterize experimental Burkholderia mallei aerosol infection in BALB/c mice. Sixty-five mice were infected with 5000 [approx. 2.5 median lethal doses (MLD)] B. mallei strain ATCC 23344(T) bacteria by the aerosol route. Bacterial counts within lung, liver, spleen, brain, kidney and blood over 14 days were determined and histopathological and immunocytochemical profiles were assessed. Mortality due to B. mallei infection occurred between days 4 and 10 post-infection. Bacterial numbers were consistently higher in the lungs than in other tissues, reaching a maximum of approximately 1.0 x 10(6) c.f.u. ml(-1) at 5 days post-infection. Bacterial counts in liver and spleen tissue remained approximately equal, reaching a maximum of approximately 1.0 x 10(4) c.f.u. ml(-1) at day 4 post-infection. By day 14 post-infection, bacterial counts were in the range 1.0 x 10(3)-1.0 x 10(4) c.f.u. ml(-1) for all tissues. Infection of the lungs by B. mallei resulted in foci of acute inflammation and necrosis. As infection progressed, the inflammatory process became subacute or chronic; this was associated with the development of extensive consolidation. Lesions in liver and spleen tissue were typical of those that might be expected in bacteraemia or bacterial toxaemia. These results suggest that the BALB/c mouse is susceptible to B. mallei when delivered by the aerosol route and that this represents a model system of acute human glanders that is suitable for research into the pathogenesis of and vaccines against this disease.

Allogeneic red blood cell transfusion is an independent risk factor for the development of postoperative bacterial infection

BACKGROUND AND OBJECTIVES

Allogeneic red blood cell transfusions may exert immunomodulatory effects in recipients including an increased rate of postoperative bacterial infection. It is controversial whether allogeneic transfusion is an independent predictor for the development of postoperative bacterial infection.

METHODS

We analysed a prospectively collected database of 1,349 patients undergoing colorectal surgery in 11 centres across Canada. The primary outcome was the development of either a postoperative wound infection or intra-abdominal sepsis in transfused and nontransfused patients. The effect of allogeneic transfusion on postoperative infection was evaluated with adjustment for all the confounding factors in a multiple regression analysis.

RESULTS

The 282 patients who received a total of 832 allogeneic units had a significantly higher frequency of wound infections and intra-abdominal sepsis than the patients who were not transfused (25. 9 vs. 14.2%, p = 0.001). A significant dose-response relationship between transfusion and infection rate was demonstrated. Multiple regression analysis identified allogeneic transfusion as a statistically significant independent predictor for postoperative bacterial infection (OR 1.18, 95% CI 1.05-1.33, p = 0.007). Other independent predictors were anastomotic leak, repeat operation, patient age and preoperative haemoglobin level. The mortality rate was also significantly higher in the transfused group.

CONCLUSION

These data support the hypothesis that allogeneic red cell transfusion is an independent risk factor for the development of postoperative bacterial infection in patients undergoing colorectal surgery. This association provides further reason to minimise exposure to allogeneic transfusions in the perioperative setting.

Prospective audit of cytomegalovirus-negative blood product utilization in haematology/oncology patients

The transfusion management of immunocompromised patients often requires special blood product use such as cytomegalovirus (CMV)-negative cellular products, which are more costly than standard blood products and occasionally in short supply. We audited the use of CMV-negative products in haematology/oncology patients to determine the appropriateness of their use. A concurrent-prospective audit was conducted of all orders for CMV-negative packed red blood cell (PRBC) and platelet products in 201 haematology/ oncology patients. Once CMV serostatus was determined, orders for inappropriate CMV-negative units were cancelled, and filled as CMV untested units. During the 21-month period of this audit, the rates of inappropriate transfusions decreased for PRBC from 73.2% to 14.3% (chi2 = 68.4, P<0.001) and for platelets from 68.1% to 10.6% (chi2 = 65.6, P<0.001). The median time to cancellation of inappropriate CMV-negative orders was 11 days. This audit resulted in estimated cost savings of $16500 over the 21-month duration. Inappropriate requests for scarce and expensive blood products are substantially reduced by concurrent-prospective auditing of transfusion practice, in a manner that is both simple and cost effective.

In vivo resistance to simian immunodeficiency virus superinfection depends on attenuated virus dose

Infection of macaques with attenuated simian immunodeficiency virus (SIV) induces potent superinfection resistance that may be applicable to the development of an AIDS vaccine but little information exists concerning the conditions necessary for the induction of this vaccine effect. We report that only a high dose of attenuated SIVmac protected macaques against intravenous challenge with more virulent virus 15 weeks after primary infection. Three of four animals given 2000-20000 TCID50 of SIVmacC8, a molecular clone of SIVmac251(32H) with a 12 bp deletion in the nef gene, essentially resisted superinfection with uncloned SIVmac. In two animals challenge virus was never detected by PCR and in one animal challenge virus was detected on one occasion only. Although animals given 2-200 TCID50 of attenuated virus were superinfected they were spared from the loss of CD4 cells seen in infected naive controls. Protection from superinfection did not correlate with immune responses, including the levels of virus-specific antibodies or virus-neutralizing activity measured on the day of challenge; although, after superinfection challenge, Nef-specific CTL responses were detected only in animals infected with high doses of attenuated SIV. Unexpectedly, cell-associated virus loads 2 weeks after inoculation were significantly lower in animals infected with a high dose of attenuated SIV compared to those in animals infected with a low dose. Our results suggest that the early dynamics of infection with attenuated virus influence superinfection resistance.

Detrimental effects on villus form during conventional oral rehydration therapy for diarrhoea in calves; alleviation by a nutrient oral rehydration solution containing glutamine

This paper examines the possibility that treatment of diarrhoea with conventional oral rehydration solutions (ORSs) may be detrimental to villus structure by imposing nutrient deprivation and that such detrimental effects may be reduced or avoided by using a nutrient ORS. A conventional WHO-type ORS (W) was compared with two nutrient solutions (N and G) both containing high glucose concentrations and the latter containing glutamine; their effects on enteric structure were assessed by morphometric analysis of samples obtained from diarrhoeic calves after 96 h treatment. Comparisons were also made with samples from controls and diarrhoeic calves at the stage where oral rehydration would have begun in the treated groups. As in our previous ORS studies, diarrhoea was induced with enterotoxigenic Escherichia coli (09:K30:K99). We measured villus length and width, crypt depth and width and calculated villus surface area in proximal, mid and distal small intestine (PSI, MSI, DSI), using standard morphometric techniques. Proximal and distal spiral colon samples (PC, DC) were examined for crypt depth and width; mitoses per crypt were counted in samples from all regions. Non-diarrhoeic calves showed the expected gradient of villus length through PSI, MSI and DSI, hence data for each region are normalized as a percentage of the control value for that region. PSI showed the greatest loss of villus length and surface area (50%) with diarrhoea. In MSI and DSI the villus loss was greater with solution W and N or G, as were increased mitoses and crypt depth. Crypt depth and mitoses also increased in the colon with solution W. Colonic crypt width increased with diarrhoea and conventional oral rehydration but less so with G; there is reason to believe that such changes have functional significance. Crypt changes in colon, MSI and DSI were least with solution G. The changes developing in diarrhoeic calves prior to treatment were thus less apparent in those treated with a nutritional ORS, particularly if it contained glutamine.

Experimentally assessed public health risks associated with pigs from farms experiencing anthrax

Following an outbreak of anthrax in an intensive pig rearing unit in north Wales in 1989 a study was initiated by the Ministry of Agriculture, Fisheries and Food to assess public health risks during such an outbreak. Of 50 pigs infected by the addition of Bacillus anthracis spores to their feed, two died of anthrax six and eight days later. The remainder were observed for 21 days and exhibited only mild and transient clinical signs of disease. As judged by the results of bacteriological culture of appropriate tissues from the survivors, it was concluded that meat from healthy pigs killed 21 days after the latest case during an outbreak would not pose a public health risk.

Macaques infected with attenuated simian immunodeficiency virus resist superinfection with virulence-revertant virus

Macaques infected with attenuated simian immunodeficiency virus (SIVmac) can resist superinfection challenge with virulent virus, showing the potential of live attenuated virus as an AIDS vaccine. Superinfection resistance does not, however, prevent the generation of virulent virus in vivo, suggesting that such virus may circumvent the resistance effect. Here, we show that three macaques already infected with the attenuated molecular clone SIVmacC8 were resistant to superinfection with virulent virus that arose in vivo following repair of a 12 bp attenuating lesion in the nef/3' LTR. In contrast, four naive animals became infected following inoculation with blood taken from the macaque in which virulent virus arose. Loss of nef-specific cytotoxic T lymphocyte (CTL) responses followed repair of the attenuating lesion within nef in the donor animal, suggesting the possibility of escape from CTL-driven selection pressure.

Macaques infected with live attenuated SIVmac are protected against superinfection via the rectal mucosa

Good protection against systemic challenge in the SIVmac model of AIDS has been provided by prior infection with attenuated virus. To determine if such protection extends to intrarectal mucosal challenge two molecular clones, SIVmacC8 and SIVmacJ5, were used in this study. SIVmacC8 has an attenuated phenotype in vivo, due to a 12-bp deletion in the nef/ 3'-LTR, whereas SIVmacJ5 has a full size nef open reading frame and induces AIDS in infected macaques. The J5 molecular clone was shown to infect rhesus macaques following atraumatic intrarectal inoculation. The dynamics were similar to those following intravenous inoculation resulting in early, high, cell-associated viremia and seroconversion. Four macaques previously infected with the attenuated SIVmacC8 resisted superinfection with SIVmacJ5, following intrarectal inoculation. These animals also resisted intrarectal infection with an HIV/SIV chimeric virus (SHIV) composed of SIVmac239 expressing the HXBc2 env, tat, and rev genes, suggesting that immunity to the envelope proteins was unlikely to be involved in the superinfection resistance. Infection with the attenuated SIVmac generated cytotoxic T lymphocytes (CTL) detectable in the peripheral circulation, serum neutralizing antibodies, and SIV-binding antibodies in rectal fluids. SIVmacC8 proviral DNA was found in lymph nodes removed at necropsy but there was no evidence for local sequestration of challenge virus. SIV-specific CTL, were detected in gut-associated lymph nodes and may have a role in limiting superinfection following mucosal exposure.

Constitutive expression of major histocompatibility complex class II antigens on monocytes and B cells correlates with disease in simian immunodeficiency virus-infected rhesus macaques

Constitutive host factors that influence progression to AIDS are understood poorly. In the macaque model for AIDS, 35 animals infected with simian immunodeficiency virus (SIV) were analyzed for major histocompatibility complex class II antigen expression on blood monocytes and B cells by immunostaining and flow cytometry. Expression varied widely between animals but was constant with time. Level of expression and the proportion of monocytes and B cells that expressed class II were not affected by SIV infection. Significantly more animals developed AIDS in the group with low class II expression than in the group with high expression (P < .001). Progression to disease was faster in animals that expressed poorly (P < .01), and opportunistic pathogens were more common (P < .05). Thus, the constitutive level of class II antigen expression may be a useful prognostic indicator for human immunodeficiency virus disease in humans and may be an important factor in the design of vaccine trials.

The lesions of rotavirus infection in 1- and 10-day-old gnotobiotic calves

Age-related resistance to rotavirus disease has been described with some rotaviruses. In the present study, we investigated age-related resistance to rotavirus disease by defining extent of intestinal infection, virus replication, and severity of intestinal lesions in groups of three 1- and 10-day-old gnotobiotic calves of mixed breed inoculated orally with a cloned bovine rotavirus of low virulence for calves (strain C3-160) and in two groups of three uninoculated control calves of mixed breed. One-day-old calves inoculated with rotavirus developed diarrhea 26 hours after inoculation, and their feces contained 10(8.5)-10(9.2) TCID50/g feces; inoculated 10-day-old calves did not develop diarrhea, virus excretion commenced on the second or third day after inoculation, and peak concentrations of virus in feces were 10(5.7)-10(7.9) TCID50/g feces. Calves were euthanatized within 8-30 hours after the attainment of peak virus shedding while they were still shedding virus at peak levels. The mean percentage of small intestinal epithelium that was immunostained for rotavirus was three times greater in 1-day-old calves than in 10-day-old calves, and the large intestine was infected more extensively in 1-day-old calves. Immunostaining for rotavirus was maximal in the mid small intestine. Staining of mucin was substantially less in the epithelium of the small intestines and colon of rotavirus-inoculated 1-day-old calves than in age-matched controls. The mean height of villi was reduced to approximately half that of controls in the mid and distal small intestine of rotavirus-inoculated 1-day-old calves and was unchanged in 10-day-old calves. Mean crypt cell production rates were greater than that in controls in both groups of rotavirus-inoculated calves, indicating increased enterocyte loss. Age-related resistance to disease was not due to an inability of rotavirus to infect and replicate in enterocytes with lethal effects but appeared to be associated with a slowing of the pathogenic process, which occurred because insufficient enterocytes became infected and destroyed for lesions to develop.

Repair and evolution of nef in vivo modulates simian immunodeficiency virus virulence

Experimental evidence from the simian immunodeficiency virus (SIV) model of AIDS has shown that the nef gene is critical in the pathogenesis of AIDS. Consequently, nef is of considerable interest in both antiviral drug and vaccine development. Preliminary findings in two rhesus macaques indicated that a deletion of only 12 bp found in the overlapping nef/3' long terminal repeat (LTR) region (9501 to 9512) of the SIVmacC8 molecular clone was associated with reduced virus isolation frequency. We show that this deletion can be repaired in vivo by a sequence duplication event and that sequence evolution continues until the predicted amino acid sequence of the repair is virtually indistinguishable from that of the virulent wild type. These changes occurred concomitantly with reversion to virulence, evidenced by a high virus isolation frequency and load, decline in anti-p27 antibody, substantial reduction in the CD4/CD8 ratio, and development of opportunistic infections associated with AIDS. These findings clearly illustrate the capacity for repair of small attenuating deletions in primate lentiviruses and also strongly suggest that the region from 9501 to 9512 in the SIV nef/3' LTR region is of biological relevance. In addition, the ability of attenuated virus to revert to virulence raises fundamental questions regarding the nature of superinfection immunity.

Number and distribution of T lymphocytes in the small intestinal mucosa of calves inoculated with rotavirus

An understanding of the immune response to rotavirus is needed to develop effective prophylaxis. There is evidence that cell-mediated responses may be involved and to extend these observations, rotavirus antigen and the three major T cell subsets, BoCD4+, BoCD8+, and BoWC1+ gamma/delta lymphocytes were immunostained in tissue sections from calves killed at 2, 4, 6, 8 and 10 days post inoculation and quantified by image analysis. It was established that in control calves, BoCD4+ lymphocytes were predominantly in the lamina propria, while the majority of BoCD8+ and BoWC1+ gamma/delta lymphocytes were in the epithelium. Rotavirus infection was seen throughout the small intestine with the greatest amount of viral antigen detected at 4 days post inoculation in the mid and distal small intestine. Increased numbers of all subsets were detected; small increases in intraepithelial BoCD4+ and BoWC1+ gamma/delta T lymphocytes were observed especially in the distal small intestine, while larger increases in BoCD8+ cells were detected in the epithelium and lamina propria of the proximal, mid and distal small intestine. The timing and location of these increases in T lymphocyte subsets is indicative of a specific immune response involving BoCD8+ and BoWC1+ gamma/delta T lymphocytes.

An investigation of temporary workshop clusters reacting with cells of the mononuclear phagocytic system

Monoclonal antibodies (mAbs) within ten temporary workshop clusters (TC3, TC8, TC9, TC11, TC16, TC17, TC19, TC20, TC21 and TC31) which from preliminary evidence appeared to recognize molecules expressed by cells of the mononuclear phagocytic system were studied by immunohistology and flow cytometry. A number of mAbs were identified that were potentially useful for immunohistological studies of the mononuclear phagocytic system. The results confirmed the specificity of a number of CD11a, CD11b, CD11c and CD44 mAbs. The findings also indicated that for several TCs the mAbs could not be regarded as recognizing the same molecule.

Histochemistry and morphology of porcine mast cells

Mast cells have been described extensively in rodents and humans but not in pigs, and the objective of this study was to characterize porcine mast cells by histochemistry and electron microscopy. Carnoy's fluid proved to be a good fixative but fixation with neutral buffered formalin blocked staining of most mast cells. Alcian Blue stained more mast cells than did Toluidine Blue (pH 0.5), although Alcian Blue also stained goblet cells. In pigs, unlike rodents, the Alcian Blue method did not distinguish between mast cells in the intestinal mucosa and those in the connective tissue of the intestinal submucosa, tongue and skin. Mast cells were significantly larger in adult pigs than in piglets; in adult pigs and piglets, mast cells in the intestinal mucosa were significantly larger than those in submucosal connective tissue, and they were more varied in shape in piglets and adults. Granules in mast cells in the intestinal mucosa stained less intensely than those in mast cells in connective tissue of tongue, skin and intestinal submucosa. Mast cells in the connective tissue of the tongue, skin and intestinal submucosa fluoresced strongly when stained with berberine sulphate or with a mixture of berberine sulphate and Acridine Orange, but mast cells in the intestinal mucosa did not. All mast cells reacted positively in an enzyme-histochemical method previously used to detect human tryptase but not in a method previously used to detect human chymase. Mast cells in the medulla of thymus stained similarly to mast cells in the intestinal mucosa. Ultrastructural differences between mast cells were not detected.

Variation in rotavirus virulence: a comparison of pathogenesis in calves between two rotaviruses of different virulence

Variation in virulence between two bovine rotaviruses was investigated using ten female and ten male 10-day-old gnotobiotic calves of five breeds or cross breeds that were inoculated with a virulent strain or a strain of low virulence. Similar numbers of infectious viral particles were detected in feces of calves inoculated with either virus, but diarrhea, xylose malabsorption, and reduction of villus height occurred only after inoculation with virulent virus. The mean percentage of the area of the villus epithelium per villus immunostained for rotavirus antigen was eight times greater in calves inoculated with virulent virus, and the mean percentage of villi on which immunostained enterocytes were detected was twice as large in calves inoculated with virulent virus than in calves inoculated with the virus of low virulence. Mean crypt death and mean crypt cell production rates were increased after inoculation with either virus. Virulence was associated with extensive spread of infection through the small intestine, preferential colonization of the proximal small intestine, and marked damage to enterocytes and villi. The virus of low virulence infected the proximal small intestine poorly, and although it infected more enterocytes in the mid and distal small intestine and replicated in them, causing cytopathic effects, it did not damage intestinal structure and affect function.

A study of the basis of virulence variation of bovine rotaviruses

Rotaviruses are enteric pathogens of cattle but sub-clinical infections are common. Virulence variation has been identified with bovine rotaviruses and some rotaviruses replicated without clinical signs in non-immune calves. The rotavirus genome is composed of eleven segments of double-stranded RNA and the fourth largest segment codes for a non-glycosylated surface protein, VP4, which has been linked with virulence. In the present study the biological basis of rotavirus virulence variation was studied in vivo and compared with the known properties of the fourth gene. Calves were inoculated orally with a virulent rotavirus or a rotavirus of low virulence which multiplied but failed to cause diarrhoea. They were taken for necropsy at intervals of 2 days after inoculation. Clinical signs, virus in faeces and the percentage of infected small intestinal epithelium were determined. Damage to the small intestine was assessed by measurement of villus heights and crypt-cell production rates. Virulence was associated with a greater level of colonization of the small intestinal epithelium, greater enterocyte damage and preferential infection of the upper small intestine. The fourth gene determines the ability of rotaviruses to spread in vitro and the finding that virulence was associated with greater colonization in vivo raises the possibility that this gene may have an important role in rotavirus virulence.

Aspects of conversational style-linguistic versus behavioral analysis

Skinner's functional analysis of verbal behavior has been contrasted with formal linguistic analysis which studies the grammatical structure and "meaning" of verbal response-products, regardless of the circumstances under which they are produced. Nevertheless, it appears that certain areas of linguistic analysis are not entirely structural. In her recent books That's Not What I Meant (1986) and You Just Don't Understand (1990), the linguist Deborah Tannen purports to explain how people exhibit different "conversation styles"-that is, how they speak and achieve effects on listeners in different ways. There are indications, however, that the linguistic model may not be the most functional and precise one that could be used in analyzing conversational style. This paper takes concepts presented in Deborah Tannen's book That's Not What I Meant (1986), analyzes them from a linguistic and a behavioral perspective, and compares the relative utility of the two approaches.

Follicle associated epithelium of the gut associated lymphoid tissue of cattle

The morphology of the gut-associated lymphoid tissue of the small and large intestine in three gnotobiotic calves was examined by scanning and transmission electron microscopy, and the distribution of specialized membranous cells present in the follicle associated epithelium was defined. Isolated follicles remaining in the ileum of a cow after involution of the continuous Peyer's patch were examined by scanning electron microscopy. The presence of membrane-bound particles, reported to be exclusively associated with the continuous Peyer's patch, was investigated in other gut-associated tissue of the small and large intestine of the calf. The presence of two types of follicle associated epithelium in the small intestine of the calf was confirmed, and the follicle associated epithelium of the large intestine proved to be a homogeneous population of specialized membranous cells, similar to that of the continuous Peyer's patch of the small intestine. In the discrete Peyer's patches, some specialized membranous cells were completely hidden by adjacent enterocytes and could only be identified by cytoplasmic extensions into the intestinal lumen. In the proximal part of the continuous Peyer's patch, a transitional zone was detected where the follicle associated epithelium of some doomed villi was composed of a homogeneous population of specialized membranous cells, while the epithelium covering other doomed villi consisted of a mixture of absorptive and specialized membranous cells, usually only found in the discrete Peyer's patches. Membrane-bound particles were observed associated with gut-associated lymphoid tissue in the small and large intestine.

Attaching and effacing lesions in vivo and adhesion to tissue culture cells of Vero-cytotoxin-producing Escherichia coli belonging to serogroups O5 and O103

Certain isolates of Escherichia coli from humans and animals with enteric disease attach to enterocytes and cause 'attaching and effacing' (AE) lesions. E. coli strain S22-1, serotype O103:H2, isolated from a child with diarrhoea, contained two plasmids; one of these (pDEP12) hybridized with the CVD419 DNA probe derived from a plasmid found in E. coli O157:H7 and associated with expression of fimbriae and ability to adhere to Intestine 407 cells. Strain S102-9, serotype O5:H-, isolated from a calf with dysentery, contained six plasmids, one of which also hybridized with the CVD419 probe. Loss of pDEP12 coincided with reduced adhesion to HEp-2 or Intestine 407 cells cultured in vitro; reintroduction of this plasmid restored adhesiveness. Loss of the plasmid in strain S102-9 that hybridized with the CVD419 probe did not cause a decrease in adhesion. Accumulations of actin were seen in vitro in the fluorescence actin staining (FAS) test of strains S22-1, S102-9 and their derivatives, irrespective of the plasmid content of these strains or the prevalence of attached bacteria. Strain S22-1 and its plasmidless derivative caused AE lesions of equal severity in experimentally infected gnotobiotic piglets; piglets inoculated with an isolate from a healthy human or pig did not develop these lesions.(ABSTRACT TRUNCATED AT 250 WORDS)

Effects of age and diet on small intestinal structure and function in gnotobiotic piglets

The effects of age and dietary change on the structure and function of piglet small intestine were investigated in gnotobiotic pigs. The small intestinal mucosa was damaged when gnotobiotic pigs were weaned on to a pelleted meal diet; villus height, crypt cell production rate, and activities of brush border enzymes were reduced. Small intestinal damage was associated with reduced weight gain over a three week period; diarrhoea was not observed. The continuous consumption of meal appeared to perpetuate the intestinal damage for three weeks, although evidence of intestinal repair, as indicated by an increased crypt cell production rate, was present three weeks after weaning. Antibodies to soya antigen were detected in serum after weaning and the intestinal damage could have been caused by antibody-mediated immune reactions to soya proteins. Villi of milk fed gnotobiotic pigs shortened significantly with age.

Effects of dietary change and rotavirus infection on small intestinal structure and function in gnotobiotic piglets

The combined effects of weaning and rotavirus infection on small intestinal structure and function and on growth rate were studied in 28 gnotobiotic piglets. There was little damage by rotavirus to the proximal small intestine, some damage to the mid small intestine and relatively severe damage to the distal small intestine; villi were stunted, crypts lengthened and activities of all brush border enzymes decreased. The damage was short-lived despite the synchronisation of rotavirus infection with simulated weaning. There was no evidence of persistent damage to the small intestine and growth rate was unaffected.

Natural infection with an attaching and effacing Escherichia coli in the small and large intestines of a calf with diarrhoea

Attaching and effacing Escherichia coli were identified in the small and large intestine of a calf with naturally occurring diarrhoea. The organisms were associated with intestinal lesions and were identified by immunoperoxidase staining and transmission and scanning electron microscopy, but they did not produce Shiga-like toxin (verotoxin).

Pathology of calves with diarrhoea in southern Britain

Twenty-one moribund calves with diarrhoea were purchased from 11 farms, their faeces examined for enteropathogens and samples of intestinal tissue removed under anaesthesia. Lesions and presence of enteropathogens on the mucosal surface were scored by histological examination of immunostained paraffin sections. Two or more enteropathogens were detected in 19 calves. Cryptosporidium appeared to be the principal cause of diarrhoea in six calves, rotavirus in four, Salmonella typhimurium in two, bacteria adherent to the surface of the large intestine in two, coronavirus in one and K99+ Escherichia coli in one calf. Diarrhoea in four calves was the consequence of mixed infections in which no one enteropathogen appeared to predominate. In one calf no enteropathogen was detected. Diarrhoea was associated with infections and lesions throughout the small and large intestines. The enteropathogens most frequently associated with lesions in the small intestines were rotavirus, coronavirus and cryptosporidium; in the large intestines they were coronavirus and bacteria apparently adherent to the mucosal surface.

The pathogenesis of turbinate atrophy in pigs caused by Bordetella bronchiseptica

The pathogenicity of 3 strains of Bordetella bronchiseptica designated B58, PV6 and B65 was compared by intranasal infection of gnotobiotic piglets. Strain B58 was a phase 1 isolate that produced haemolysin, an adhesin for calf erythrocytes, adenylate cyclase, mouse lethal factor, dermonecrotic factor and cytotoxin. B65 was a variant of B58 that produced no detectable haemolysin, adhesin or adenylate cyclase and 10-fold smaller amounts than B58 of mouse lethal factor, dermonecrotic factor and cytotoxin. Strain PV6 was a phase 1 isolate that produced only haemolysin, adhesin and adenylate cyclase. After nasal infection of gnotobiotic pigs, 10(3.2)-10(6.2) colony forming units ml-1 (cfu ml-1) of strains B58 and PV6 were cultured from nasal washings during the next 25 days. In contrast, only 10(1.0)-10(2.8) cfu ml-1 of strain B65 were recovered during the same period. Only pigs infected with strain B58 had turbinate atrophy when they were slaughtered 25 days after infection and neutralising antibody to cytotoxin was detected only in these pigs. These results suggested that the cytotoxin, which may be the same as the mouse lethal and dermonecrotic factors, was the cause of turbinate atrophy. They also support the view that the adhesin for calf erythrocytes is required for colonisation of the nasal cavity in vivo.

Comparison in gnotobiotic pigs of lesions caused by verotoxigenic and non-verotoxigenic Escherichia coli

To compare the pathogenesis of calf and rabbit strains of E. coli, gnotobiotic pigs were infected with 10(10) colony forming units (cfu) of verotoxigenic strain RDEC-1 or S102-9, or a non-verotoxigenic E. coli (X114/83). Pigs were killed 4 days later, and intestinal tissue was fixed and examined by light, scanning, and transmission electron microscopy. Strains S102-9 and RDEC-1 caused diarrhea, attached to enterocytes, and effaced microvilli, confirming that the calf and rabbit strains possessed similar mechanisms of pathogenicity. Non-verotoxigenic strain X114/83 did not cause diarrhea, but in 5/5 piglets it was detected in histological sections adherent to enterocyte surfaces. Exfoliated enterocytes were seen in 4/5. Bacteria attached to enterocytes by "cups" and "pedestals," with effacement of microvilli, were seen by electron microscopy in 1/5 piglets. It was concluded that strain S102-9 appears to be an animal equivalent of human enterohemorrhagic E. coli, that verotoxin is not essential in the pathogenesis of attaching and effacing lesions, and that the lesions induced by S102-9 are more severe in gnotobiotic pigs than in gnotobiotic or conventional calves.

Dysentery in calves caused by an atypical strain of Escherichia coli (S102-9)

Dysentery lasting 4-8 days was produced in five 4-day-old colostrum-fed calves, after inoculation with an atypical strain of Escherichia coli S102-9; peak excretion of S102-9 occurred during the period of dysentery. Two calves were killed when clinical signs were most severe and bacteria were seen attached to the surfaces of enterocytes in the large intestine; microscopic lesions were seen in these areas. The lesions were identical to those previously reported in a natural outbreak of dysentery in calves, from which E. coli S102-9 was isolated, and to those seen in gnotobiotic calves experimentally infected with S102-9. Reinfection of the three surviving calves 16-20 days later with S102-9 and primary infection of two calves aged 24 and 51 days did not cause dysentery. Four of 659 coliforms isolated from field outbreaks of calf diarrhoea resembled the atypical strain S102-9. These four isolates and S102-9 did not produce heat-stable enterotoxin, but all produced a toxin cytopathic for Vero and HeLa cells. Two of the four isolates were inoculated alone into 4-day-old gnotobiotic calves deprived of colostrum; neither calf developed dysentery but microscopic lesions identical to those produced by S102-9 were detected in the large intestines of both animals.

Pathology of natural rotavirus infection in clinically normal calves

During a longitudinal study of the epidemiology of rotavirus infection in a calf rearing unit, excretion of virus in faeces was detected by enzyme-linked immunosorbent assay in 40 of 48 (83 per cent) unweaned calves aged between three days and five weeks. Fifty per cent of the infected calves had no clinical signs of disease. Enterocytes containing rotavirus antigen and intestinal lesions were found in all of 12 clinically normal calves selected for necropsy between days 1 and 4 of virus excretion. Stunting and fusion of villi, exfoliation, disarrangement and vacuolation of enterocytes and the presence of cuboidal enterocytes were observed in infected calves but not in rotavirus-free control calves. Lesions predominated in the upper small intestine, where rotavirus was most abundant, especially on the first two days of virus excretion. The numbers of enterocytes infected with rotavirus diminished before the lesions resolved.

Dysentery caused by Escherichia coli (S102-9) in calves: natural and experimental disease

A dysentery syndrome was recognized among the Institute's calves at 18 to 21 days of age. It was reproduced experimentally in gnotobiotic calves with an atypical Escherichia coli (S102-9) isolated from the affected calves. In both natural and experimental disease the calves passed copious bright red blood in the feces and developed diarrhea. Walls of the colon and rectum were thickened, and the mucosa was reddened and covered by an exudate that contained mucus and blood clots. Bacteria were seen closely adherent to the luminal surfaces of enterocytes, often in cup-shaped depressions or on cytoplasmic pedestals. Microvilli were distorted, disorientated or absent. There was exfoliation of infected enterocytes and a mild acute inflammation of the underlying lamina. In two of five calves with natural disease, the adherent bacteria did not stain by the immunoperoxidase method with antisera raised against E. coli (S102-9). This indicated that there was possibly more than one bacterial cause of the syndrome. Lesions in experimentally infected calves were indistinguishable from those produced by some E. coli which are enteropathogenic for man, rabbits, and pigs.

Plasma enteroglucagon and neurotensin levels in gnotobiotic calves infected with enteropathogenic and non-enteropathogenic viruses

Five gnotobiotic calves were each infected with five viruses. Each calf was inoculated with coronavirus at seven days old, followed by astrovirus, Newbury agent, parainfluenzavirus type 3 and rotavirus at intervals of two weeks. Three of the viruses were enteropathogenic (bovine coronavirus, bovine calici-like virus and bovine rotavirus) and two were not (bovine astrovirus and parainfluenzavirus type 3). Plasma levels of the peptide hormones enteroglucagon and neurotensin and faecal output were measured daily and xylose absorption was studied before and after each infection. A close correlation was found between a rise in plasma enteroglucagon and neurotensin and infection with enteropathogenic viruses. The three enteropathogenic viruses caused increased daily faecal output, and elevated plasma levels of enteroglucagon and neurotensin, while the non-enteropathogens did not. The calici-like virus and rotavirus but not the coronavirus caused xylose malabsorption.

Studies on the relationship between coronaviruses from the intestinal and respiratory tracts of calves

An immunofluorescence test on smears of nasal epithelial cells was used to detect coronavirus infection in the respiratory tract of calves. Thirteen gnotobiotic calves were infected with coronavirus isolates derived from faeces or respiratory material: virus was detected in faeces and nasal swabs from all animals. In 115 calves from a field survey, there was a significant association between coronavirus excretion from both respiratory and enteric routes in calves with diarrhoea. In a further 12 calves, at necropsy, the predilection sites for coronavirus growth were the distal small intestine, large intestine and the epithelia of the nasal cavity and trachea. Antigen was not found in lung tissue by immunofluorescence or immunoperoxidase staining. Infection with enteric coronavirus induced immunity to reinfection and to heterologous challenge with two coronavirus isolates derived from the respiratory tract. Nine coronaviruses were cultivated, cloned and antisera to three were prepared in pigs. There was complete virus neutralisation in tests with homologous sera and significant cross reactions with the eight other isolates which were of intestinal and respiratory origin. Thus, these bovine coronavirus isolates belonged to the same serotype despite the source of virus.

Localisation of enteropathogens in paraffin embedded tissue by immunoperoxidase

An indirect immunoperoxidase technique has been used to identify enteropathogens in formol-sublimate fixed paraffin embedded sections of calf intestine. Infections with bovine rotavirus, bovine coronavirus, Newbury agent SRV -1, and K99+ Escherichia coli have been detected in the intestines from experimentally infected and conventially reared diarrhoeic or normal calves. The ability to visualize enteropathogenic agents in histological sections resulted in the demonstration of virus infected cells at sites not previously shown to be infected using the immunofluorescence technique.

Lesions of gnotobiotic calves experimentally infected with a calicivirus-like (Newbury) agent

Fourteen gnotobiotic calves were killed 0.5 to ten days after infection with Newbury agent SRV-1 and the changes in small intestinal structure and function were assessed, qualitatively and quantitatively, by light microscopy, scanning and transmission electron microscopy, enzymology and xylose absorption. The first enterocytes detected as infected by immunoperoxidase were those on the sides of villi at the base. Subsequently exfoliation of degenerate enterocytes resulted in stunted villi; mucosal beta-galactosidase activity fell and there was xylose malabsorption. Small intestinal damage, first detected at 12 hours after infection but almost repaired by ten days, was restricted to the anterior half of the small intestine. In the distal small intestine, where no virus-induced damage occurred, villi lengthened--possibly due to increased mitosis of crypt cells stimulated by enteroglucagon release.

Characterization of a calici-like virus (Newbury agent) found in association with astrovirus in bovine diarrhea

A bovine calici-like virus and astrovirus, present in the same fecal sample from an outbreak of diarrhea, were separated from each other by calf passage. The calici-like virus (Newbury agent SRV-1) caused anorexia, diarrhea, and xylose malabsorption in gnotobiotic calves aged 17 to 60 days, whereas the bovine astrovirus was nonpathogenic in similar calves. The calici-like virus was shown to be antigenically distinct from a previously described isolate (Newbury agent SRV-2) by two-way cross-protection experiments in calves; calves immune to homologous challenge became clinically ill and excreted virus when challenged with the heterologous virus.

Quantitation of small intestinal structure and function in unthrifty piglets

Litters of piglets were weighed at birth, weaning and five weeks later; pairs of thrifty and unthrifty weaned pigs were identified. Small intestinal structure and function were studied in 28 eight-week-old age-matched littermate pairs and in 16 weight-matched littermates. A comparison of age-matched piglets showed changes in mucosal structure in unthrifty piglets, a slight reduction in absorptive function but no biochemical evidence of small intestinal disease. Morphometric studies of weight-matched piglets revealed no differences between thrifty and unthrifty piglets, suggesting that the differences in the age-matched groups may have been an effect of body-weight. If unthrifty pigs grew slowly as a result of small intestinal damage and malfunction immediately after weaning no evidence of it remained when they were studied five weeks later.

Responses of fluke-infected and fluke-free cattle to experimental reinfection with Salmonella dublin

Cattle, aged nine to 18 months, were given sublethal doses of Salmonella dublin either intravenously, orally on two occasions, or by contact for 19 to 22 weeks with a persistent excretor. When challenged by intravenous injection of 10(9) S dublin at 10 to 22 weeks after their first exposure to S dublin 22 out of 36 animals survived. All similarly challenged cattle, which had not been previously exposed to S dublin, died. Infection with Fasciola hepatica did not alter the ability of cattle to survive reinfection with S dublin but the bacteria persisted in the tissues and were excreted in the faeces of fluke-infected animals for longer than in fluke-free animals. The ability to survive reinfection and to eliminate S dublin from the tissues was apparently unrelated to agglutinating antibody titres or delayed hypersensitivity.

Transport of cyclic adenosine 3',5'-monophosphate across Escherichia coli vesicle membranes

The uptake and efflux of cyclic adenosine 3',5'-monophosphate (3',5'-cAMP) by Escherichia coli membrane vesicles were studied. Metabolic energy was not required for the uptake process and was found to actually decrease the amount of 3',5'-cAMP found in the vesicles. 3',5'-cAMP uptake exhibits saturation kinetics (Km = 10 mM, Vmax = 2.8 nmol/mg of protein per min) and was competitively inhibited by a number of 3',5'-cAMP analogs. The uptake of 3',5'-cAMP was found to be sharply affected by a membrane phase transition. The excretion of 3',5'-cAMP was studied by using everted membrane vesicles. Efflux in this system was dependent upon metabolic energy and was reduced or abolished by uncouplers. Different energy sources powered efflux at different rates, showing a relationship between the degree of membrane energization and rate of excretion of 3',5'-cAMP. The efflux process also displayed saturation kinetics (Km = 10.0 mM, Vmax = 0.98 nmol/mg of protein per min) and was competitively inhibited by the same 3',5'-cAMP analogs and to the same degree as was the uptake process. 3',5'-cAMP was found to be chemically unaltered by both the uptake and excretion processes. These data are interpreted as showing that the uptake and excretion of 3',5'-cAMP in E. coli membrane vesicles are carrier-mediated phenomena, possibly employing the same carrier system. Uptake is by facilitated diffusion whereas efflux is via an energy-dependent, active transport process. Evidence is presented showing that cells can regulate the number of 3',5'-cAMP transport carriers. The rate of 3',5'-cAMP excretion is possibly regulated by both the degree of membrane energization and the number of carriers present per cells.